Question

Of the students in a certain homeroom, 9 are in the school play, 12 are in the

Answer 1

31 students are in the home room.

Answer 2

9+12+15=36

36 students are there because the question says 5 students participate in exactly 2 out of 3 activities

                   which is = 36-5=31
and the rest participate in only 1 activity = 31 participate in 1 activity
therefore total 36 students were there in the homeroom
hope it helps!!